1. Field of the Invention
The present invention relates to a fuel injection valve mainly used in a fuel supply system of an internal combustion engine, and particularly to an improvement of a fuel injection valve which comprises a valve seat member which has at one end portion a valve seat and an outlet hole penetrating through a central portion of the valve seat, a valve body which is housed in the valve seat member and operates to open and close the valve seat, and an injector plate which is joined to one end surface of the valve seat member and has a plurality of fuel injection holes disposed to be spaced radially outward from the outlet hole; in which a funnel-shaped fuel collecting recess for collecting a fuel passing through the valve seat and guiding the fuel to the outlet hole is provided between the valve seat and the outlet hole, and a flat fuel diffusion chamber which diffuses radially outward the fuel passing through the outlet hole and guides the fuel to the plurality of fuel injection holes is provided between opposed surfaces of the valve seat member and the injector plate.
2. Description of the Related Art
Such an electromagnetic fuel injection valve is already known as disclosed in, for example, Japanese Patent Application Laid-open No. 2000-97129.
In such a fuel injection valve, at the time of valve opening of the valve body, a fuel passing through the valve seat is guided to the outlet hole by the fuel collecting recess, reverses its flow to the fuel diffusion chamber from the outlet hole, is diffused radially outward and injected through a plurality of fuel injection holes of the injector plate, thereby forming spray forms.
Incidentally, in the conventional fuel injection valve, the inner peripheral surface of the outlet hole has a cylindrical shape, and a right angle or a near-right angle is formed between the bottom surface of the fuel collecting recess and the inner peripheral surface of the outlet hole, and between the inner peripheral surface of the outlet hole and the ceiling surface of the fuel diffusion chamber. Therefore, when the flow of the fuel reverses in the outlet hole, a number of eddies is generated inside the reverse flow, and causes increase in pressure loss of the fuel to decrease the injection amount, inhibition of atomization of the injection fuel from the fuel injection holes, instability of the direction and shape of the spray forms, and the like.